The center will employ a wide range of techniques to explore neurobiological substrata for actions of drugs of abuse. Snyder will evaluate several areas with a particular focus on four. (A) The function of the mitochondrial benzodiazepine receptor will be studied by examining the roles of the three protein subunits of the recently isolated receptor protein. (B) Molecular mechanisms of smell and taste will be elucidated as a means to understanding recognition systems and desensitization involved in responses to drugs. (C) Mediation by nitric oxide of the neurotoxicity of drugs will be investigated. (D) Two continuous clones of human cerebral cortical neurons in culture will be characterized. In Mains' laboratory peptide processing in the developing anterior pituitary corticotropin will be clarified focusing on the effects of steroids and endoproteases. A mutant strain of rats dependent on ascorbate will help elucidate the role of ascorbate in peptide alpha-amidation and norepinephrine formation. Acute and chronic actions of cocaine on peptide synthetic enzymes in brain and pituitary and peptide processing in hippocampal cultures will be evaluated. Eipper will use dopaminergic regulating of pituitary melanotropes as a test system to determine whether expression of peptide processing enzymes (three subtilisin-like endoproteases, the exoprotease carboxypeptidase H, the peptide alpha-amidating enzyme and the transmembrane electron transport protein cytochrome b-561) can serve as a reliable indicator of peptidergic function in the CNS. In Baraban's laboratory immediate early genes regulated by dopamine, amphetamine and cocaine will be investigated. Three members of the Zif family of transcription factors will be studied as well as two forms of Fos B. The behavioral sensitization to amphetamine and cocaine that occurs when these are injected into midbrain dopamine cell bodies will be explored in terms of the role of Zif and Fos transcription factors in eliciting these behaviors.